After the Luftwaffe had laid waste to much of east London during the blitz, the first living things to return to the bombsites were not people, but weeds. By the time the BBC announced Hitler's suicide in May 1945, bracken was marching up the aisle of St James's, Piccadilly, thornapple was blooming through Cheapside cellars and ragwort had scaled London Wall. Rosebay willowherb (previously an upland rarity) was now spreading so aggressively through the unhealed rubble that east Londoners had rechristened it bombweed.

There's something eerie about weeds – their speed, their ingenuity, their almost supernatural resourcefulness. "Shape-shifters," Richard Mabey calls them. Many of the most successful species will slide up a size or down a shade of colour if it helps ensure their survival for another generation. They'll also adapt to an astonishing level of abuse and rough treatment – the harder the better, in fact. Plantain likes to be trodden underfoot. Danish scurvy-grass thrives on the salty turbulence of motorway central reservations. Buddleia relishes vertical surfaces with no apparent soil at all: walls, car park concrete, railway bridges. Dandelions joyride in the windscreen grilles of cars and sycamores sprout in chimney pots. If it wasn't for the fact that they're plants, it would be tempting to wonder whether they have a sense of humour.

And if their adaptability is astounding, then so is their tenacity. Professor Edward Salisbury, director of Kew from 1943-1956, once cultivated 300 plant species from the dirt he found in his trouser turn-ups. Bindweed alone can put down roots to a depth of 18 feet, spread 30 square yards in a season and germinate its own seeds after 40 years. As Mabey points out: "A bindweed root or stem chopped into 100 pieces by a frustrated gardener is simply the starting point for 100 new plants."

Of course, the very concept of a weed is an entirely human one. The old saying still holds – a weed is just a plant in the wrong place. Or, sometimes, the wrong time. The Romans esteemed nettles so highly as pot-herb, medicine and raw material that when they invaded Britain they brought their own varieties. Ground elder was introduced here as a remedy for gout. Rhododendrons remain beloved by many gardeners despite being a menace to native woodlands. And half the plants in Britain's great physic gardens are simultaneously valued medicines and garden pests – yarrow, comfrey, burdock, heartsease.

Over the centuries, people have tried every conceivable method of getting rid of the plants they don't like. Medieval farmers hoped curses and name-calling might work: hellweed, devil's claws, devil's fingers, devil's daisy, devil's tether. They tried suing. Then they tried farming. But everywhere humans went, the weeds always danced just a little way ahead. All large-scale agriculture did was to provide cover for species such as wild oats to mimic the appearance of a host crop. Systematic hand-weeding opened up more space for deep-rooted plants. Ploughing galvanised those in search of disturbed ground. Pesticides encouraged mutation. Herbicides did more damage to us than to the plants. If this is a battle, then the weeds are winning.

Which brings us to the other obvious thing about them – their relationship to us and with us. We may hate them, but there is no question that they succeed as they do partly through our efforts. Large areas of Florida are now under threat from paperbark trees introduced to the Everglades in order to drain the land and thus make it suitable for development. And as Mabey notes, the UK's three Most Wanted superweeds were all deliberately introduced to this country.

Giant hogweed, Indian balsam and Japanese knotweed were each brought to Britain in the mid-19th century as garden ornamentals. It didn't take long before giant hogweed went native, absconded from its original home in Buckingham Palace Gardens and colonised London's canal system. Knotweed went one step further, demonstrating a Hulk-like ability to rip through pavement slabs and muscle through brickwork. It's now considered such a threat that eradication programmes cost the taxpayer £150m a year.

Richard Mabey writes about weeds with the confident affection of someone discussing old friends – which many of these plants must now be. Back in 1972, he went for a walk from his office in London and happened upon what he called the "unofficial countryside": abandoned or forgotten scraps of the city in which plants and wildlife thrived. At the time his interest in those urban scraps was taken as no more than a hippy-ish novelty, but in the years since he took that first walk, the rest of the world has caught up with him. Urban planners have recently made the astounding discovery that plants and wildlife can get on with being beautiful and regenerative without any outside assistance. When weeds colonised an abandoned section of New York's high-rise railroad, the inhabitants of the Upper West Side were split between those who wanted the High Line demolished and those who liked looking out on a vagrant landscape of irises, daffodils and rogue Christmas trees. The preservationists won and the High Line reopened in 2009 as Manhattan's newest slice of urban parkland.

Mabey's amble through the low-level, high-rise world of weeds is rich in lore and usefulness. As in all his work, what comes over is his abiding passion for plants and the sustenance they give both imaginatively and spiritually. Even his chapter on triffids – the botanical nightmares of fiction and fact – offers not a ghastly vision of a mutant future, but a cheerful portrait of occasional horticultural villains seizing their moment of notoriety before vanishing back to the undergrowth. This time around, Mabey has given us something that is as much a celebration of the vexed coupling between mankind and plantlife as it is a fine marriage between subject and author.

Bella Bathurst is a writer and photographer. Her next book, The Bicycle Book, is published by HarperPress in the spring